Wetlands, such as marshes and riparian forests, are lively as well as lovely places.
Wading birds like the great blue heron hunt in water, but require trees for roosting and nesting.
Marshes and ponds provide happy hunting grounds for small predators as well as large ones. Dragonflies are not generally found in mid-ocean or deep forest, but instead in those places where water meets land-based vegetation.
An ordinary twig on the edge of a well-traveled waterside path gives these deadly little insects a good perch for hunting.
Moving to a different kind of edge, I must confess to being startled the first time I noticed a red-tailed hawk hanging out along Interstate 77, not having realized that hawks make use of the wooded edges of our highways. From a raptor's perspective, a high perch next to a mowed area helps in the search for tasty little rodents.
Not all edges are created equal, however. In general, mowed areas are not as good for wildlife as areas left in a somewhat wilder state.
This butterfly garden, while quite a fine thing, has limited use for small mammals because of the large, closely-mowed area that separates it from an adjoining grassland; chipmunks and rabbits venturing across that expanse would be easy pickings for a hawk (one of which was circling overhead when this picture was taken, no doubt hoping that some unwary creature would do exactly that).
Perhaps my favorite edges are grasslands adjoining woods, which seem to make everybody happy: trees, shrubs, forbs, insects, birds, rabbits and rodents--they're all there, wandering around gorgeous tangles like this one near Akron.
And as many of us have discovered, sometimes to our great annoyance, the edge habitats we have created in our yards are just perfect for deer.